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E1523. Latissimus Dorsi and Teres Major Myotendinous Injuries in Professional Athletes: Imaging Characterization, Management, and Outcomes
Authors
  1. Redmond-Craig Anderson; Keck Hospital of USC
  2. Ellen Chang; Keck Hospital of USC
  3. Jordan Gross; Keck Hospital of USC
  4. Eric White; Keck Hospital of USC
  5. Dakshesh Patel; Keck Hospital of USC
  6. Anderanik Tomasian; Keck Hospital of USC
Background
Latissimus dorsi (LD) and teres major (TM) myotendinous injuries have been increasingly recognized as source of pain and potential disability in recent years in professional athletes, particularly baseball pitchers. These injuries are often challenging to recognize clinically due to lack of characteristic physical exam findings. As delayed or missed diagnoses can be debilitating, prompt and accurate imaging diagnosis is crucial. Although non-operative management has been the mainstay of treatment for the majority of injuries, decline of several athletic performance metrics has been demonstrated with a conservative approach and investigators have successfully implemented surgical repair for a subset of patients. As clinical decision for potential surgical intervention is primarily based on imaging findings, precise characterization of injuries is critical and directly influences patient care. In this review, the authors will discuss normal anatomy, imaging characterization and classification of LD and TM myotendinous injuries and their clinical implications for treatment approaches.

Educational Goals / Teaching Points
1) To review normal and variant LD/TM myotendinous (illustrative) anatomy as well as mechanisms of injury, 2) To describe injury patterns, as well as characterization/classification (grading) of LD and TM myotendinous injuries on magnetic resonance (MR) and ultrasound, 3) To discuss differential diagnoses, and 4) To understand the treatment implications, options, and clinical outcomes.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
LD and TM muscles are active in the late cocking, acceleration, and follow-through phases of pitching. Considering complex anatomy, MR is the most commonly utilized imaging modality for evaluation of suspected LD/TM injuries, offering the added benefit of assessment for alternative diagnoses with similar clinical presentation. A tailored MR protocol should be implemented, including large field-of-view sequences to include much of the posterior chest wall with axial, oblique coronal and sagittal planes obtained along LD/TM myotendinous units. Short TR/TE sequences are beneficial for evaluation of anatomy while fat-saturated fluid-sensitive sequences are most useful for characterization and grading of injury. An MR grading system has been developed recently to classify injuries (Grades I-IV). Grade I: muscular/myotendinous strain with no tear; Grade II: Partial-thickness tear at any site from muscle origin to tendon insertion; Grade III: Full-thickness tear with less than 2 centimeters (cm) of tendinous retraction; Grade IV: Full-thickness tear with greater than 2 cm of tendinous retraction. Grade III and IV injuries are subdivided into “A” and “B” subcategories, indicating tear at the humeral insertion and myotendinous junction, respectively.

Conclusion
Injuries to LD/TM myotendinous units are increasingly recognized clinically, particularly in the overhead throwing athlete. Understanding imaging characteristics and accurate imaging diagnosis of such injuries are critical for timely and appropriate management, and for improved outcomes.